This is makeindex, version 2.15 [TeX Live 2010] (kpathsea + Thai support).
Scanning input file ../html/manual-Z-I.idx....
!! Input index error (file = ../html/manual-Z-I.idx, line = 395):
   -- Illegal null field.
!! Input index error (file = ../html/manual-Z-I.idx, line = 396):
   -- Illegal null field.
done (584 entries accepted, 2 rejected).
Sorting entries........done (6009 comparisons).
Generating output file ../html/manual-Z-I.ind....done (652 lines written, 0 warnings).
Output written in ../html/manual-Z-I.ind.
Transcript written in ../html/manual-Z-I.ilg.
